Hot hose cold hose
 

My 1972 164,

When I came back earlier from approximately 15 mile drive I notice some coolant on the bonnet. Upon opening the bonnet coolant was leaking from the top hose. The top of the radiator and top hose were very hot but the bottom of the radiator and bottom hose were barely Luke warm.

Any ideas welcome

Many thanks
Steve

it could have been the icy air around , was the TEMP Gauge in the Normal central position?

It looks like Volvo stuck with the down flow top tank / bottom tank rad through the complete production run. If you can, running your hand down the fins to check for temperature differences. That may give you a clue as to what is going on. If the radiator fins mid way down the rad have a significant temperature drop chances are you have a blockage in the rad. Try running let to right to confirm the location of the blockage.

Even with a completely blocked radiator, if the thermostat is opening you will eventually get hot coolant into the top tank resulting in a hot top hose and tank. You could have a sludge blockage in the radiator; but, that usually does not happen all of a sudden. The problem gets gradually worse, usually showing up in hot weather. Plymouth does not look like it has had seriously cold weather. Highs and lows all look to be above freezing. If you have been exposed to below 0C for any significant period of time what is the freezing point for your coolant solution? A pile of slush in the rad will do an excellent job of blocking flow.

How is your coolant pump? Is the drive belt slipping / gone missing / pump seized?

The top tank being hot suggests the thermostat is opening; but, the correct Volvo thermostats have a jiggle valve and even if the thermostat has failed shut the jiggle valve will eventually pass enough hot coolant to heat the top tank; but, that will take a while.

What was your dash temperature gauge doing while all of this was happening?

Hello 142 guy, thank you for your reply. The gauge was reading half way. The belts are all new and correctly tensioned. The water pump is approximately 8 months old.

The coolant was replaced at the same time as the water pump.

I’ll be taking her out over the weekend ans monitor it closely and report back

Thanks again 👍

If the gauge was reading mid temperature, perhaps you didn't have an over heating event. If the air temperature was cool it would be normal for the lower hose to feel cooler.

Check you coolant reservoir level. When the engine is cold the level should be between the min level and middle. If you fill the reservoir too full when cold there is not enough expansion room left in the bottle once the engine comes up to temperature. Normally, that results in the expansion cap venting fluid from the top of the reservoir; but, if your hose clamps on the top rad hose were a little loose it will leak from the path of least resistance.